Chart For Jet Design

Discussion in 'Jet Drives' started by navarch_hish, Sep 14, 2006.

  1. navarch_hish
    Joined: Jun 2006
    Posts: 18
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: India

    navarch_hish Junior Member

    I am designing a jet drive based on the ship trust and Vs/Va.

    I am looking for a chart which is a plot of Vs/Va and Vs/Vj (jet ratio)..

    it has an optimum effciency line, what we do based on the ship's Vs/Va we find out Vs/Vj for optimum efficiency..

    I am lookn for the chart, can anyone provide me the chart, it will be really helpful for my project work..

    here

    Vs= ship speed
    Va = Velocity of advance

    Vj= velocity of water at jet outlet..

    ALso can anyone tell me jet effeciency applicable for cataramans operating in the range of 35 knots?
     
  2. alpamis34
    Joined: Jul 2006
    Posts: 63
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    Location: A city that never sleeps-Istanbul

    alpamis34 Senior Member

    Hi mate,
    The initial issue while designing a jet propulsion is to take the Vin/U ratio into account where Vin is the velocity of the flow in the duct just after the water intake gap. U is the velocity of the downstream flow ,basically the domain beneath the hull. If this ratio is too low, the duct will end up with a choked flow and if it is high then it will have erosion aand cavitation problems.

    I dont have the charts on my pc but I have some on the books and as I have read from them , the efficiency of the waterjet prop. comes above 30 35 knots.I might give you some info as I go more throughly.

    Cheers
     
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